for a function like this:
int i(int b)
{
int i1,i2,i3;
return i1 + i2;
}
in x86, compile with gcc -fno-pic -fomit-frame-pointer -gstabs -O0 -S
the output is:
Lscope1:
.stabs "i:F(0,1)",36,0,0,i
.stabs "b:p(0,1)",160,0,0,-20
.globl i
.type i, @function
i:
.stabn 68,0,10,.LM5-.LFBB2
.LM5:
.LFBB2:
.LFB1:
.cfi_startproc
movl %edi, -20(%rsp)
.stabn 68,0,12,.LM6-.LFBB2
.LM6:
movl -8(%rsp), %eax
movl -4(%rsp), %edx
leal (%rdx,%rax), %eax
.stabn 68,0,13,.LM7-.LFBB2
.LM7:
ret
.cfi_endproc
.LFE1:
.size i, .-i
.stabs "i1:(0,1)",128,0,0,-4
.stabs "i2:(0,1)",128,0,0,-8
.stabs "i3:(0,1)",128,0,0,-12
.stabn 192,0,0,.LFBB2-.LFBB2
.stabn 224,0,0,.Lscope2-.LFBB2
Everything works as expect:
the offsets for both parameters and locals are negative, no matter in
stabs directive or in the assembly code. And the offset value in stabs
equals to the one in the code.
But for mips, mipsel-linux-gcc -fno-pic -fomit-frame-pointer -gstabs -O0
-S output is:
scope1:
.align 2
.stabs "i:F(0,1)",36,0,0,i
.stabs "b:p(0,1)",160,0,0,24
.globl i
.ent i
.type i, @function
i:
.stabn 68,0,10,$LM5
$LM5:
$LFBB2:
.set nomips16
.frame $sp,24,$31 # vars= 16, regs= 0/0, args= 0, gp= 8
.mask 0x00000000,0
.fmask 0x00000000,0
.set noreorder
.set nomacro
addiu $sp,$sp,-24
.cprestore 0
sw $4,24($sp)
.stabn 68,0,12,$LM6
$LM6:
lw $3,16($sp)
lw $2,12($sp)
nop
addu $2,$3,$2
.stabn 68,0,13,$LM7
$LM7:
addiu $sp,$sp,24
j $31
nop
.set macro
.set reorder
.end i
.stabs "i1:(0,1)",128,0,0,-8
.stabs "i2:(0,1)",128,0,0,-12
The local variable offsets in stabs are negative, but in the code they are
positive. For my understanding of fpc logic, they should both generated
from loc.reference.offset or something similiar, they cannot be different.
If I am not making mistake, we have to special case some code to make
debugging work.
Am I wrong?
Regards
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